The present invention relates to aerosol canisters and particularly to improved actuator caps suitable for mounting on such canisters.
Hand-held aerosol cylindrical dispensers are known that are filled with material to be dispensed through a nozzle by a propellant gas. Frequently the product is dispensed as a finely divided spray, but may alternatively be dispensed as a foam or a relatively thin jet.
A typical aerosol canister has a valve mounted at its upper end, to which a delivery mechanism is mounted.
The valve often has a short projecting tube (a valve stem) on which the delivery mechanism is mounted, although sometimes the delivery mechanism may project into the canister through an aperture to make contact with the valve. A dip tube usually extends downwardly from the valve into the canister, up which product is forced by a propellant when the valve is opened.
Small button actuators with nozzles are known for use with such aerosol dispensers. Some button actuators release product as a result of downward pressure on the actuator, while others release product in response to sideways pressure on the actuator (depending on the type of valve used). The button actuators can be installed by being pushed down on to the valve stem (due to a friction fit of the valve stem in a lower bore of the button actuator).
A separate overcap typically fits onto the cylindrical canister to protect the button actuator from accidental operation. However the use of a separate cap which has to be removed before the button actuator can be accessed is inconvenient. To overcome the disadvantages of a separate cap, caps have been developed that incorporate actuator features so that they can be left in place on the canister when the aerosol dispenser is used.
For example, U.S. Pat. No. 3,058,626 discloses a cap whose diameter is substantially the same as that of the canister on which it is mounted and which has a depressed valley running across the top of the cap. There is a separate actuator button mounted on the valve underneath the outer cap. The valley portion of the cap mentioned above may be depressed to depress the underlying actuator button. Spray passes from the nozzle in the actuator button through a frontal aperture in the protective cover (which is kept in alignment with the nozzle by a rib in the cover which slides within a groove in the actuator button). Unfortunately, there is no good means of holding the actuator button on the cover so that they can be handled as a unit.
An improved overcap system is described in PCT/GB96/03208. However, that system relies on a somewhat complex receiving pod in an actuator overcap to retain and align the actuator button. The pod can be difficult to use with certain types of automated assembly equipment.
There is thus a need for an improved overcap for use with aerosol dispensers.